This grant application proposes to extend the use of biomagnetic measurement into a relatively new research area- - the study of fetal heart activity. Presently, ultrasound is the only method used clinically to assess heart activity of the human fetus. Development of a completely safe, noninvasive technique that provides complementary information could have great significance. Potential clinical applications include detection of fetal heart anomalies and fetal distress associated with hypoxia or acidemia. There is strong theoretical justification for the use of magnetic detection for fetal assessment. Pilot studies presented here clearly document these advantages. The primary purpose of the proposed research is to test the hypothesis that FMCG can be employed to measure clinically important parameters of fetal cardiac function over a wide range of gestation ages. Fetuses with abnormal heart function will be included in the study. The study data will also yield detailed new information regarding fetal heart rate variability and spatiotemporal properties of the FMCG. The specific aims to be achieved are as follows: 1) To measure FMCG waveform parameters in fetuses and neonates with normal and abnormal heart function, including PR interval, QRS duration, PR-RR correlation, and fetal heart vector. 2) To characterize and study the development of fetal heart rate variability over a wide range of gestational age, 3) To develop methods to accurately measure position and orientation of the fetus in utero so that their influence on the FMCG can be studied and FMCG mapping data can be displayed with respect to the fetus.